1. Field of the Invention
The present invention relates to a board and method for forming a graphene layer, and more particularly, to a board for use in forming a graphene layer, which has a structure able to improve properties of the graphene layer formed thereon, and to a method of forming a high-quality graphene layer using the same.
2. Description of the Related Art
Graphene is a two-dimensional (2D) thin film resulting from planar arrangement of carbon atoms, and has a variety of advantages, including high electronic mobility, excellent mechanical strength, high transparency, etc. Furthermore, graphene may be currently manufactured using a processing technique such as deposition, etc., which is typically used, and is thus receiving attention as a next-generation material.
A graphene layer having the above properties is conventionally formed in such a manner that a silicon carbide (SiC) board is annealed at a high temperature in a high vacuum or that graphite oxide dispersed in a solvent is reduced. Recently, formation of a graphene layer using chemical vapor deposition (CVD) is mainly utilized due to its ability to form a graphene layer having a large area at low cost.
The method of forming a graphene layer using CVD is performed by exposing a catalyst metal such as nickel (Ni), copper (Cu), etc., to a high temperature in a gas atmosphere including a hydrocarbon such as methane (CH4) or acetylene (C2H2) so that graphene is grown on a metal thin film, and this method facilitates growth of a desired layer on a large area and has low processing costs and is thus known to be the most appropriate in terms of commercialization among the methods of manufacturing graphene.
However, this method is problematic because, while grains of a metal thin film are grown in the course of high-temperature annealing for thermal decomposition of a hydrocarbon gas and formation of the graphene lattice of carbon, a deep grain boundary is formed and thus the surface of the metal thin film becomes very rough, which causes the quality of graphene formed on such a metal thin film to degrade. For example, in the case of a Ni metal thin film having a thickness of 300 nm, when it is annealed at 800° C. for growth of graphene, the depth of the grain boundary thereof may amount to 100 nm. Also, in the case where graphene in monolayer form with a thickness of less than 1 nm is grown on the metal thin film, bumpy shaped graphene is grown depending on the curvature of the surface of the metal thin film. When this graphene is transferred to a silicon wafer or a glass wafer, curvature formed along the grain boundary of the metal thin film is wrinkled while being pressed, undesirably deteriorating electrical properties of graphene.
As an alternative to decreasing the grain boundary of the metal thin film, a method of lowering a processing temperature is taken into consideration. However, when the processing temperature is lowered to decrease the grain growth of metal, the quality of graphene becomes poor. Hence, methods able to improve crystallinity of a metal thin film and decrease surface roughness thereof while not lowering the processing temperature should be ensured.